Schoenbeck Interests Presentation

John Schoenbeck
BME Senior Capstone Project – Fall 2012
Dr. Mansoor Nasir
 Injuries to the Anterior Cruciate Ligament (ACL) are one of the most common knee injuries amongst athletes involved in running & jumping sports.
 The ACL can be sprained or torn. Many sprains and nearly all torn ACL’s must be surgically repaired.
 Roughly 150,000 ACL Injuries occur annually in the United States alone, this amounts to an estimated $500 million in healthcare costs.  Recovery time ranges from six to twelve months. (Livestrong.com)
 The current gold standard for ACL replacement is to notch out a wide piece of the Patellar Tendon (PT) and use it as a graft. This method has a very high harvest site morbidity and a very low success rate. The PT graft yields to the changes in its load dynamics and looses a large portion of its function as a result.
 Xenografts carry a very high risk for immune response and disease transmission, especially in cases of Rheumatoid Arthritis.
 There is an outstanding need in the field of surgical ligament repair for improved ACL autografts and allografts to be used in lieu of the current cut‐and‐
paste method.
 To engineer ligament tissues that can be produced in‐vivo and used for ligament reconstructive/replaceme
nt surgery
 To produce a biomimetic scaffold that enhances cell proliferation and extracellular collagen matrix formation.
 Take steps toward producing a stronger and more viable engineered ligament.
Biomimetic Architecture
 Micro: Porosity, Linear Guidance
 Macro: Structural Patterns, Aspect Ratios
Biocompatible Materials
 Surface Features, Degradation, Matl. Mechanics
Cell Behavior
 Response to environmental stimuli
 Targeted phenotype determination
 For the purpose of exploring novel three‐
dimensional braid patterns in engineered ligament tissues; two novel and one state‐of‐
the‐art braid designs will be used for characterization.
 Dr. Li’s scaffold is based upon the ligament fibril triple‐helix feature. It produces a bumpy, semi‐
cylindrical structure with overall axial micro‐
groove alignment. This braid is also the easiest to mechanically reproduce.
 John’s scaffold is based upon the ligament’s crimped, wavy feature. It produces a structure with easily controlled dimensions and maximal dynamic strength. This braid will require advanced mechanical equipment to reproduce.
 The Drexel scaffold is a hybrid of the thin, wide structure of ligament tissue and the helix braid concept. It produces a structure with a fixed thickness and overall axial micro‐grooves.
Scaffold Fiber Identified Model
Model Name
Structure
Expected Benefits
Potential Limitations
Dr. Li’s Novel Scaffold
Second‐order triple helix; Intended to mimic the triple helix architecture of native fibrils
Axial microgrooving,
enhanced tensile strength,
localized stability in Substructure
Poor lateral integrity, fixed cross sectional aspect ratio, potential for smothering
John’s Novel Scaffold
6 fiber triple helix serpentine weave; Intended to mimic the crimped macrostructure of native ligaments.
Axial microgrooving, toe region in elongation curve, straight‐through channel design
Lateral fiber pattern, segments of poor lateral integrity, potential for smothering
Drexel State‐
of‐the‐Art Scaffold
8 fiber diagonal basket weave; Proven to produce enhanced structural properties when compared with 2D flat fiber scaffolds.
Axial microgrooving, potential toe region, highly reproducible, proven model
Poor lateral integrity, no parallel component with respect to axis of strain
 All references used for this research project and experimental design proposal are available in summary format upon request.
 Questions/Corrections/Conside
rations?
 Livestrong.com